JP2009225963A - Manufacturing method of flexible tube for endoscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a flexible tube for endoscopes for heat-welding a shell with high efficiency while suppressing variations in manufacture. <P>SOLUTION: The manufacturing method of a flexible tube for endoscopes includes a tube coating process (st1) in which first and second tubular heat-shrinking tubes having different heat shrink ratios coat respective peripheral surfaces of the first and second shells which have different softening temperatures at a distal end side and a proximal end side in the longitudinal direction of the flexible tube for endoscopes and are made of a thermoplastic resin, a heating process (st2) for heating the first and second shells simultaneously at the same temperature by placing the flexible tube for endoscopes in a furnace, and a tube peeling process (st3) for peeling the first and second heat-shrinking tubes from the respective peripheral surfaces of the first and second shells. The variations in the manufacture are suppressed in the heating process by controlling to have the inside of one furnace at one temperature. If the second shell is insufficiently softened, reheating is not required since the second shell is tightened by the second heat-shrinking tube. Consequently, heat-welding of the shells is performed with high efficiency and at a low cost. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a flexible tube for an endoscope using a plurality of types of thermoplastic resin shells having different softening temperatures.

  Conventionally, when manufacturing a flexible tube used for an insertion portion of an endoscope, a metal strip is spirally wound to form a flex (spiral tube), and the outer periphery of the flex is a blade (mesh tube) Cover it with a flexible tube material (inner parts). Next, the outer surface of the flexible tube material is covered with a thermoplastic resin-made outer skin. Thereafter, the flexible tube material is heated to a high temperature in a furnace to melt the outer skin and perform a thermal welding process for joining the surface of the blade and the inner peripheral surface of the outer skin.

  In this thermal welding process, the outer skin is not limited to the inner peripheral surface but is melted to the outer peripheral surface, which may cause wrinkles on the outer peripheral surface of the outer skin. For this reason, a high melting point layer having a melting point higher than the melting point of the outer skin is provided on the outer peripheral surface of the outer skin of the flexible tube for an endoscope, and the outer peripheral surface of the outer skin is restored by heating at a temperature higher than the softening point of the outer skin. A method for manufacturing a flexible tube for an endoscope is known in which only the inner part of the outer skin is melted and the outer peripheral surface of the flexible tube material is integrally and firmly fixed to the outer peripheral surface of the flexible tube material while maintaining the appearance of the above (Patent Document) 1).

  In addition, in order to improve the insertion property of the endoscope flexible tube into the body cavity, the front end side skin of the endoscope flexible tube is soft and the rear end side skin is hard, and the front and back skin resin There are two-stage specifications with different hardness. The resin used for the front end side skin has a low softening point, and the resin used for the rear end side skin has a high softening point. Therefore, in such an apparatus for manufacturing a flexible tube for an endoscope, the interior of a furnace for heating the flexible tube for an endoscope is divided into a plurality of regions for each temperature of each softening point of the outer skin. Hot air having a temperature corresponding to each region is sent (Patent Document 2).

In the manufacturing apparatus described in Patent Document 2, the temperature of the envelope of the endoscope flexible tube in the relatively high temperature (230 ° C.) region is 230 at the portion closest to the relatively low temperature (170 ° C.) region side. Since a so-called temperature gradient is generated without reaching to ° C., there arises a problem that welding of the portion becomes insufficient. Therefore, the present applicant has proposed a manufacturing method in which only the portion where the temperature gradient occurs is reheated with a spot heater (Japanese Patent Application No. 2007-313695).
Japanese Patent No. 3602580 JP 2006-110153 A

  In the manufacturing apparatus described in Patent Document 2 and the manufacturing method described in Japanese Patent Application No. 2007-313695, the heating temperature is set in one furnace in the entire heating process of heating the entire flexible tube for endoscope. Since it is divided into a plurality of different regions, it is difficult to manage the heating temperature, and manufacturing variations are likely to occur. Moreover, in the manufacturing method described in the above Japanese Patent Application No. 2007-313695, since the reheating process using a spot heater is performed after the entire heating process, the heat treatment process becomes twice and the efficiency is low, resulting in high costs. Was found to occur.

  The present invention has been made to solve the above-described problems, and provides a method for manufacturing a flexible tube for an endoscope which can suppress the manufacturing variation and perform heat welding of the outer skin with high efficiency. With the goal.

  The method for manufacturing a flexible tube for an endoscope according to the present invention includes a spiral tube formed by spirally winding a strip and an outer peripheral surface of an elongated flexible tube material including a mesh tube covering the outer periphery. In a method for manufacturing a flexible tube for an endoscope, wherein first and second outer shells made of thermoplastic resins having different softening point temperatures due to heating on the distal end side and the rear end side in the longitudinal direction of the flexible tube material are welded. A tube covering step of covering the outer peripheral surfaces of the first and second skins with cylindrical first and second heat shrinkable tubes having different heat shrinkage rates, respectively, A heating step of performing the welding by simultaneously heating the first and second skins covered with the first and second heat shrinkable tubes at a temperature corresponding to the lower one of the softening points; In addition, the first and second heat shrinkable tubes are peeled off from the outer peripheral surfaces of the first and second outer skins. Characterized in that it consists of a degree.

  In addition, the temperature of the softening point of the first outer skin is lower than that of the second outer skin, and the first heat shrinkable tube covered on the first outer skin is lower than the second heat shrinkable tube covered on the second outer skin. It is preferable that the heat shrinkage rate is low.

  Further, as a step before the tube covering step, a step of covering the outer peripheral surface of the flexible tube material with the tube-shaped first and second outer skins in a state where the adjacent end surfaces are in close contact with each other is provided. It is preferable.

  Further, in the tube covering step, the abutting position where the end surfaces of the first and second heat shrinkable tubes are in close contact with each other is more than the abutting position where the end surfaces of the first and second outer skins are in close contact with each other. It is preferable to be on the outer skin side.

  Moreover, it is preferable that the process before shape | molding the said 1st, 2nd outer skin by extrusion molding is provided in the outer peripheral surface of the said flexible tube raw material as a process before the said tube coating process.

  Moreover, it is preferable that the transition part which changed the mixing ratio gradually is provided in the boundary of the said 1st, 2nd outer_layer | skin.

  According to the method for manufacturing a flexible tube for an endoscope of the present invention, a cylindrical shape having a different thermal contraction rate is provided on each outer peripheral surface of the first and second outer shells made of thermoplastic resins having different softening temperatures. The first and second heat-shrinkable tubes are respectively covered, and the first and second outer skins are simultaneously heated at a temperature corresponding to the lower softening point of the first and second outer skins. Since the first and second heat-shrinkable tubes are peeled off from the outer peripheral surfaces of the first and second skins after being welded to the front end side and the rear end side in the longitudinal direction, the first and second softening points have different temperatures. It is not necessary to control the temperature by dividing the inside of the furnace into a plurality of areas for each outer shell, or to reheat a portion where welding is insufficient with a spot heater. As a result, manufacturing variations can be suppressed and the outer shell can be thermally welded with high efficiency.

  In the endoscope flexible tube manufacturing method of the present invention, as shown in the flowchart of FIG. 1, the softening point temperature differs between the distal end side and the rear end side in the longitudinal direction of the endoscope flexible tube. A tube covering step (st1) for covering each of the outer peripheral surfaces of the first and second outer shells made of thermoplastic resin with cylindrical first and second heat shrinkable tubes having different heat shrinkage rates, and then an endoscope A heating step (st2) in which the flexible tube is placed in a furnace and the first and second skins are simultaneously heated at the same temperature, and then the first and second heat-shrinkable tubes are placed on the first and second skins, respectively. It consists of the tube peeling process (st3) which peels from an outer peripheral surface. Hereinafter, embodiments of the present invention will be described in detail.

  In FIG. 2 showing a state where the tube covering step is performed, inside the flexible tube 10 for endoscope, there are a flex (spiral tube) 11 and a blade (net-like tube) which is coated in close contact with the outer periphery of the flex 11. The flexible tube raw material 13 comprised from 12 is provided.

  The flex 11 includes a first flex 14 formed by winding a thin elastic strip such as stainless steel with a gap in a spiral shape, and a diameter of the first flex 11 having the same structure as that of the first flex 11. It has a double winding structure consisting of 2 flex 15s. The blade 12 is formed by braiding a plurality of strands 16 in which a plurality of (for example, about 4 to 12) strands 16a made of fine metal wires such as stainless steel or copper alloy are arranged in parallel.

  On the outer peripheral surface of the distal end side of the flexible tube material 13 inserted into the body cavity (for example, about 1/4 of the total length of the endoscope flexible tube 10), a relatively soft thermoplastic resin (for example, the temperature of the softening point). Is covered with a tube-shaped first outer skin 17 formed at a temperature of 170 ° C., and the outer peripheral surface on the rear end side (for example, about 3/4 of the total length of the flexible tube for endoscope 10) operated by the operator is covered. The tube-like second outer skin 18 formed of a thermoplastic resin harder than the first outer skin 17 (for example, the temperature of the softening point is 188 ° C.) is covered.

  The thicknesses and diameters of the first and second outer skins 17 and 18 are substantially the same, and each is covered with the outer peripheral surface of the flexible tube material 13. As the thermoplastic resin forming the outer skins 17 and 18, for example, Pandex T-8180 (trade name) and T-8195 (trade name), which are thermoplastic polyurethane elastomers manufactured by DIC Bayer Polymer Co., Ltd., are used.

  After the outer skins 17 and 18 are put on the outer peripheral surface of the flexible tube material 13, the adjacent end surfaces 17 a and 18 a of the outer skins 17 and 18 are butted together. Thereafter, the outer peripheral surfaces of the outer skins 17 and 18 are covered with first and second heat shrinkable tubes 19 and 20 that are thermally contracted by heating, respectively (st1). The heat-shrinkable tubes 19 and 20 both start heat shrinkage at the same heating temperature, for example, the softening point temperature of 170 ° C. of the first outer skin 17, but the heat shrinkage rates are different from each other. As a material of the heat shrinkable tubes 19 and 20, for example, a fluorine resin such as Teflon (registered trademark) or a silicon resin is used.

  As shown in FIG. 3, when the heat-shrinkable tubes 19 and 20 are heated alone, the inner diameters d1a and d2a before the heat-shrinkable tubes 19 and 20 are heated are loosely fitted to the outer peripheral surfaces of the outer skins 17 and 18, respectively. However, both the inner diameters d1b and d2b after heating are smaller than the outer diameters of the outer skins 17 and 18, and the inner diameter d2b of the second heat shrinkable tube 20 is the inner diameter d1b of the first heat shrinkable tube 19. Smaller than the size.

  That is, the heat shrinkage rate of the second heat shrinkable tube 20 is higher than that of the first heat shrinkable tube 19, and the force with which the second heat shrinkable tube 20 tightens the second skin 18 is greater than that of the first heat shrinkable tube 19. Stronger than the force of tightening the first outer skin 17.

  After covering the outer peripheral surfaces of the outer skins 17 and 18 with the heat-shrinkable tubes 19 and 20, the adjacent end surfaces 19a and 20a of the heat-shrinkable tubes 19 and 20 are butted together before heating. The abutting positions of the end surfaces 19a and 20a are slightly shifted to positions closer to the first outer skin 17 (the distal end of the flexible tube material 13) than the abutting positions of the end surfaces 17a and 18a. Thereby, the butting position of the end faces 17a and 18a is located below the second heat shrinkable tube 20 having a stronger tightening force than the first heat shrinkable tube 19.

  Therefore, after heating, the end faces 17a and 18a are fastened by the second heat shrinkable tube 20 having a tightening force stronger than the tightening force by the first heat shrinkable tube 19, and are firmly adhered to each other.

  After covering the outer skin 17 and 18 and the heat shrinkable tubes 19 and 20 on the outer peripheral surface of the flexible tube material 13, the outer skins 17 and 18 and the heat shrinkable tubes 19 and 20 are removed from the flexible tube material 13 as shown in FIG. 4. A flange 21 is attached to the tip of the flexible tube material 13 so as not to drop off. A weight 22 for hanging the flexible tube material 13 vertically is attached to the outside of the flange 21. With the weight 22 facing down, the rear end portion of the flexible tube material 13 is attached to the ceiling in the furnace 24 via a hanging metal fitting 23.

  For example, 20 flexible tube materials 13 are suspended in the furnace 24 at a time. When the heater 25 of the furnace 24 is driven, the outer skins 17 and 18 and the heat-shrinkable tubes 19 and 20 covered on all the flexible tube materials 13 in the furnace 24 are, for example, temperatures near the softening point of the first outer skin 17. It is heated at 170 ° C. to 175 ° C. for a certain period of time (st2). Since it is not necessary to divide the inside of the furnace 24 into a plurality of regions having different heating temperature settings, the heating temperature can be easily managed, and manufacturing variations due to variations in heating temperature can be suppressed.

  The first outer skin 17 softens when the temperature reaches the softening point, and at the same time, the first heat shrinkable tube 19 heat shrinks and presses and tightens the first outer skin 17 from the outside. As shown in FIG. The outer skin 17 is welded to the blade 12. The second skin 18 does not sufficiently soften because the temperature does not reach the softening point, but the second heat shrinkable tube 20 is thermally shrunk and the second skin 18 is tightened more strongly than the first heat shrinkable tube 19. Is tightened from the outside, so that the second outer skin 18 is in close contact with the blade 12. Further, since the end faces 17a and 18a are strongly tightened by the second heat shrinkable tube 20, they are firmly adhered to each other.

  When a predetermined heating time has elapsed, the flexible tube material 13 is taken out from the furnace 24 and cooled. Thereafter, when the heat shrink tubes 19 and 20 are cut in the longitudinal direction by a cutting means such as a cutter, and the heat shrink tubes 19 and 20 are peeled off from the outer peripheral surfaces of the outer skins 17 and 18, the inner portions as shown in FIG. The endoscope flexible tube 10 is completed (st3).

  In this way, even if the second skin 18 is not sufficiently softened, it is compensated by tightening with the second heat-shrinkable tube 20, so there is no need to reheat the second skin 18, and the skin is highly efficient and low cost. Thermal welding can be performed.

  The above-described embodiment relates to a flexible tube for an endoscope having a two-stage specification using two types of first and second outer skins having different temperatures at the softening point by heating on the front end side and the rear end side in the longitudinal direction. However, the present invention is not limited to this. Between the first and second skins, the temperature of the softening point is higher than that of the first skin, and the temperature of the softening point is lower than that of the second skin. Further, the present invention may relate to a multi-stage endoscope flexible tube having at least one third outer skin interposed therebetween. In this case, a third heat shrinkable tube having a heat shrinkage ratio between the first heat shrinkable tube and the second heat shrinkable tube is used for the third outer skin.

  For example, as shown in FIG. 7A, in the endoscope flexible tube 10 of the two-stage specification using the first and second outer skins 17 and 18, with the butting position 26 of the outer skins 17 and 18 as a boundary, The hardness of the endoscope flexible tube 10 in the longitudinal direction is greatly changed. On the other hand, as shown in FIG. 5B, a flexible tube for an endoscope having a four-stage specification in which third and fourth outer skins 27 and 28 are interposed between first and second outer skins 17 and 18. 29, there are three positions for matching different outer skins, and the change in the hardness in the longitudinal direction becomes gradual as compared to the flexible tube 10 for endoscopes of the two-stage specification, and insertion into a body cavity ( Including the operability of the surgeon). In this case, it is preferable to use third and fourth heat shrinkable tubes for the third and fourth outer skins 27 and 28, which have a heat shrinkage ratio between the first heat shrinkable tube and the second heat shrinkable tube. Note that the heat shrinkage rate of the third heat shrinkable tube is smaller than the heat shrinkage rate of the fourth heat shrinkable tube.

  In the above-described embodiment, the first outer skin and the second outer skin formed in a tube shape are applied to the flexible tube for endoscope which covers the outer peripheral surface of the flexible tube material. Without limitation, for example, the present invention may be applied to an endoscope flexible tube in which a first outer skin and a second outer skin are formed on the outer peripheral surface of a flexible tube material by extrusion molding. Hereinafter, this embodiment will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the same member as the said embodiment, and description is abbreviate | omitted.

  As shown in FIG. 8, on the outer peripheral surface on the distal end side of the flexible tube material 13 constituting the endoscope flexible tube 30, a relatively soft thermoplastic resin (for example, the temperature of the softening point is 170 ° C. by extrusion molding). ) Is formed, and the outer peripheral surface on the rear end side of the flexible tube material 13 is made of a thermoplastic resin harder than the first skin 31 (for example, the temperature of the softening point is 188 ° C.). An outer skin 32 is formed. Furthermore, at the boundary between the first skin 31 and the second skin 32, the hardness from the first skin 31 to the second skin 32 is gradually changed by gradually changing the mixing ratio of the relatively soft thermoplastic resin and the hard thermoplastic resin. There is provided a transition portion 33 that changes.

  As a manufacturing method, a container containing a soft thermoplastic resin and a container containing a hard thermoplastic resin are provided, and the discharge ports of the two containers are joined to one passage, and the flexible passage is formed in the passage. The first outer shell 31 is formed by flowing only the soft thermoplastic resin into the passage at first while passing through the tube material 13. Next, the transition portion 33 is formed by gradually adding a hard thermoplastic resin to the soft thermoplastic resin, and finally the second outer skin 32 is formed by pouring only the hard thermoplastic resin into the passage.

  As described above, the outer skins 31 and 32 and the transition part 33 are formed on the outer peripheral surface of the flexible tube material 13, but the outer skins 31 and 32 and the transition part 33 and the blade 12 may be insufficiently adhered. In such a case, the outer circumferences of the outer skins 31 and 32 are covered with the first and second heat-shrinkable tubes 19 and 20, and the end surfaces 19 a and 19 a of the first and second heat-shrinkable tubes 19 and 20 are approximately in the vicinity of the center of the transition portion 33. Match 20a.

  Thereafter, as in the above-described embodiment, when heated in the furnace 24, as shown in FIG. 9, the first and second heat-shrinkable tubes 19 and 20 are thermally shrunk, and the outer skins 31 and 32 and the transition portion 33 are moved. Since the tightening is performed from the outside, the outer skins 31 and 32 and the transition portion 33 are firmly attached to the blade 12. After being removed from the furnace 24 and cooled, the first and second heat shrinkable tubes 19 and 20 are cut and peeled off from the outer skin 31, the outer skin 32, and the transition portion 33. The flexible tube 30 is completed.

  In this embodiment, the range in which the transition portion 33 occupies the entire length of the endoscope flexible tube 10 is an extremely narrow range. However, the present invention is not limited to this, and for example, an endoscope It may be in a range close to the entire length of the flexible tube 10 for use. In this case, at least one heat shrinkable tube having a heat shrinkage ratio between the first heat shrinkable tube 19 and the second heat shrinkable tube 20 is inserted between the first and second heat shrinkable tubes 19 and 20. preferable.

  The material of the heat-shrinkable tube and the outer shell mentioned in the embodiment described above is an example, and other materials may be used as long as the material has characteristics suitable for the present invention. In addition, although the softening point temperatures of the first and second skins were set to 170 ° C. and 188 ° C., and the heat shrink start temperature of the heat shrinkable tube was set to 170 ° C., the present invention is not limited to such values. is there.

It is a flowchart which shows roughly the manufacturing method of the flexible tube for endoscopes of this invention. It is sectional drawing of the part of the flexible tube for endoscopes which shows the structure before the heating of the outer shell formed in tube shape, a heat contraction tube, and the flexible tube for endoscopes. It is explanatory drawing which shows the difference in the diameter before a heating of two types of heat shrinkable tubes from which a heat shrinkage rate differs, and after a heating. It is explanatory drawing which shows the state which put the flexible tube for endoscopes in the furnace. It is sectional drawing of a part of flexible tube for endoscopes which shows the state of the outer skin | heater and heat contraction tube after a heating. It is sectional drawing of a part of endoscope flexible tube which shows the completed flexible tube for endoscopes after peeling a heat-shrinkable tube. It is a graph which shows roughly the difference in the change of each hardness in the flexible tube for endoscopes of a two-stage specification and a multistage specification. It is sectional drawing of a part of endoscope flexible tube which shows the state before the heating of the outer_layer | sheath and heat-shrinkable tube shape | molded by extrusion molding. It is sectional drawing of a part of flexible tube for endoscopes which shows the state of the outer skin | heater and heat contraction tube after a heating. It is sectional drawing of a part of flexible tube for endoscopes which shows the flexible tube for endoscopes which peeled off the heat contraction tube and was completed.

Explanation of symbols

10, 29, 30 Flexible tube for endoscope 13 Flexible tube material 17, 31 First outer skin 17a, 18a, 19a, 20a End surface 18, 32 Second outer skin 19 First heat shrinkable tube 20 Second heat shrinkable tube 27 3rd skin 28 4th skin 33 Transition part

Claims (6)

On the outer peripheral surface of an elongated flexible tube material composed of a spiral tube formed by spirally winding a strip and a mesh tube covering the outer periphery, a front end side and a rear end side in the longitudinal direction of the flexible tube material In the method for manufacturing a flexible tube for an endoscope, the first and second outer skins made of thermoplastic resins having different softening points due to heating are welded.
A tube covering step of covering each of the outer peripheral surfaces of the first and second skins with tubular first and second heat shrinkable tubes having different heat shrinkage rates;
Next, the first and second skins covered with the first and second heat-shrinkable tubes are simultaneously heated at a temperature corresponding to the lower one of the softening points of the first and second skins. And a heating step for performing the welding,
Next, a tube peeling step of peeling the first and second heat-shrinkable tubes from the outer peripheral surfaces of the first and second outer skins. A method for manufacturing a flexible tube for an endoscope, comprising:   The temperature of the softening point of the first outer skin is lower than that of the second outer skin, and the first heat shrinkable tube that covers the first outer skin contracts more than the second heat shrinkable tube that covers the second outer skin. 2. The method for manufacturing a flexible tube for an endoscope according to claim 1, wherein the rate is low. As a step before the tube coating step,
The step of covering the outer peripheral surface of the flexible tube material with the tube-shaped first and second outer skins in a state in which the adjacent end surfaces are in close contact with each other is provided. The manufacturing method of the flexible tube for endoscopes of description.   In the tube covering step, the abutting position where the end surfaces of the first and second heat-shrinkable tubes are in close contact with each other is closer to the first outer skin than the abutting position where the end surfaces of the first and second outer shells are in close contact with each other. The method for manufacturing a flexible tube for an endoscope according to claim 3, wherein: As a step before the tube coating step,
3. The flexible tube for an endoscope according to claim 1, wherein a step of forming the first and second outer skins by extrusion molding is provided on an outer peripheral surface of the flexible tube material. Method.   6. The method for manufacturing a flexible tube for an endoscope according to claim 5, wherein a transition portion having a gradually different mixing ratio is provided at a boundary between the first and second skins.

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